How can 128 ounces = 133.5 ounces?

[naita]

@thelurkinghorror

Please elucidate. The US does not use the metric ton to any regularity, yes. My comment is that metric (which != strictly SI) is very inconsistent also. And the US uses the calorie pretty consistent with other similar countries.
Half assed = most English-speaking countries. The UK uses stones for example.

I do not understand the relevance of this part, there are many definitions of e.g. miles in the same country, but one is only used in very narrow situations.

No, it’s not “very inconsistent”. You picked two examples. Tons and calories:

The metric ton is 1.6 % off one of its non-metric namesakes, and 9.3 % off another. That’s not an inconsistency with metric.

The small and large calorie is indeed a legacy confusion in metric, but it’s hardly evidence of metric being “very inconsistent”, and unlike with the genuinely “very inconsistent” non-metric units, actual metric users have an approach to removing this one. The standard is now kilojoules and where calories are still used for legacy reasons they are always labelled kilocalories.

[bob_2]

@thelurkinghorror

Half assed = most English-speaking countries. The UK uses stones for example.

Yes we do, but only for the weight of people and some animals. No one goes into a shop and buys a stone of potatoes and if asked how heavy their car was they would never say 250 stones either.

[LSLGuy]

@Ranger_Jeff

At most altitudes, as long as you’re on the Earth, IMHO weight and mass are interchangeable. Of course, if you’re in a microgravity or on the moon or Mars, they’re not.
…

[pet peeve]

As long as you’re taking about un-accelerated non-buoyant slow-moving objects near the Earth’s surface in Earth’s reference frame and only to a couple decimal places’ precision I’ll give you that. But you need to specify all those conditions each and every time you assume or assert they’re interchangeable.

IOW, assuming mass & weight are interchangeable is a fundamental error of units and can only produce confusion. The reason ordinary people get puzzled by all this stuff is precisely because they’ve got this fundamental confusion built into the foundation of their personal physics. In the many common situations where mass & weight aren’t interchangeable their whole mental model lights up “TILT!”

It’s akin to cartoon physics: it doesn’t illuminate the truth; it obscures it.

[/pet peeve]

(I feel much better now. Thank you.)

[Colophon]

@pulykamell

Isn’t the British mnemonic something like “a pint of water is a pound and a quarter” or something to that effect? There’s an equivalent saying, but I’m not going to bother to look it up.

The version my mother used went “A pint of pure water weighs a pound and a quarter”.

In imperial measurements, a gallon (eight pints) was originally 10 pounds of water, making the 1 pint = 1.25lb equivalence exact, by definition. Nowadays, an imperial pint is 568.261ml, which weighs a little more: about 20.0356 imperial ounces, or 1.2522 pounds.

[Colophon]

Missed the edit, but the last sentence should say “Nowadays, an imperial pint is 568.261ml, which weighs a little more: about 20.044 imperial ounces, or 1.2528 pounds.”

[md2000]

@thelurkinghorror

…

I mean do you have a link? The sources I found say it’s 2 (not calculators).

I opened Google, typed in “pint to ounce”

the first thing that came up was the Google unit converter, but it will list US pint and US ounces.

Change the contents of the units to “Imperial pint” and “imperial ounces” and you will get 1 iPint = 20 iOunces.

While being bored, do the same for imperial cup, and it will claim it is 10 ounces, which has never been the case since I ever remembered my imperial measure - and believe me, before metric was instituted in Canada, unit conversions were a staple of grade school math. How many rods in a chain? How many pecks in a bushel? How many yards in a mile? How many… Etc. (more likely it’s a side effect or confusion that an imperial cup is almost 10 US ounces).

You don’t think Peter Piper was making up “pecks” for his peppers, do you?

And as I said - the logic was unassailable. For the level of accuracy necessary for the general market of the time - 1 gallon water = 10 pounds = 160 weight ounces = 160 fluid ounces. 160 was divisible by 2,4,5,8,10 - practical divisibility for the earlier marketplace for those not trained in grade 5 math. Same logic as pence-shillings-pounds. A Shilling (12 pence) could be divided by 2,3,4,6; a pound also by 5, 10, 12, 15. No need for fractions or decimal points.

However, the “cup” has no serious definition it seems and varies - I ran across one site that calls 8 imperial ounces a “Canadian cup” since the British cup has been redefined to be a round metric size, it appears (and the US cup, 8 US ounces, is different again).

I’d be curious if anyone from pre-metric Britain can chime in on what they considered a cup? I’d be surprised if it were that much different from Canadian on US cups.

[rat_avatar]

@Francis_Vaughan

I think he is trying to say that inertial mass is the same as gravitational mass. But not getting it quite right.

The clock example is a well worn one. It isn’t that the clock is running or not - it is whether it is wound up or not (pedantically, a wound clock can be stopped). A wound clock has more mass than one that has run down because of the extra energy stored in the clockspring.

But weight, unless you are a some kinds of engineer, is a force. You weigh more or less depending upon how space is curved. A large nearby mass can curve space around you, and that can change the force upon you, and hence your weight.

No I am stating that weight by using the fictional force of gravity is intrinsically a measure of mass. The “force” you feel due to gravity is due to an constant acceleration in space time as the shortest path or geodesic in spacetime is blocked. If gravity was a force it would result in a curved world lines but it tends towards geodesic paths without outside forces. The fictional force of gravity in reference to weight is like the fictional centrifugal force, it is only valid within a particular reference frame.

In the metric system you have the kilogram and the kilopond or kilogram-force which are similar to the pound-mass and pound-force concepts in the avoirdupois system. The short term pound can mean either force or mass but actually defaults to mass. Even in the SI kilogram the standard is checked by measuring the relative weights with a known standard, as was the pound until it was defined against the kilogram.

Even now that they are trying to create a more empirical measurement for the kilogram they have to correct for fluctuations in gravity to match the gravitational standard. While “weight” may not automatically adapt for differences in this constant acceleration in space time both “weight” and “mass” are measuring the same fundamental property which is the resistance of any physical object to any change in its state of motion.

[bob_2]

@md2000

I’d be curious if anyone from pre-metric Britain can chime in on what they considered a cup? I’d be surprised if it were that much different from Canadian on US cups.

As far as I know, and I have been cooking with recipes for 50 years, a “cup” was never an official weight or measure and was generally only found in American cook books. I have a book of tables from school in the late 40s/early 50s which lists all the above mentioned (and obscure even then) weights and measures. No mention of a cup there. In fact I am now wondering who and when it was that actually defined the “Cup”…

As a child in West Africa, I was aware that rice and other grains was sold in the market by something like a “cup”. In fact the universally accepted measure at that time was the 50 cigarette tin. Tis was, no doubt, due to the ready availability of a standard tin and not for any academic reason.

[Colophon]

@bob_2

As far as I know, and I have been cooking with recipes for 50 years, a “cup” was never an official weight or measure and was generally only found in American cook books. I have a book of tables from school in the late 40s/early 50s which lists all the above mentioned (and obscure even then) weights and measures. No mention of a cup there. In fact I am now wondering who and when it was that actually defined the “Cup”…

Yes, British recipes never use volumes for dry ingredients, so the idea of “cups” doesn’t really have any equivalent here. I never came across it until I first found American recipes on the internet. We use weights for flour, sugar etc.

You can buy measuring cups over here, though. I have a set of nesting ones that measure 1 cup, 1/2 cup, 1/3 cup and so on. I assume they are US cups, and I only use them if following an American recipe. I’ve never bothered to weigh out how much 1 cup of various ingredients actually is.

[AskNott]

It’s not hard to find tables to convert a cup of flour, for example, to grams and ounces. Flour and brown sugar, to a lesser extent, can be compressed, so it’s always better to go with weight when you can.

It is harder to find equivalents for fiddly bits like the imperial smidgen, imperial pinch, and imperial dash.